Presently, some semiconductor device, such as RF power transistors, function more efficiently with lowered thermal resistance of the substrate material. The thermal resistance can be lowered in a number of ways to increase device performance. The common method of lowering thermal resistance is wafer or substrate thinning. This is typically accomplished by dry or wet chemical etching or backlapping/polishing techniques. There are a number of difficulties with this approach. The materials used for the substrate in RF transistors are typically P+ Buffer on N- substrate, semi-insulating substrates or high resistivity substrates. Each of these substrates is relatively expensive and mostly discarded through the thinning process. The use of other materials, such as silicon carbide, are contemplated. While many of these materials provide good thermal conductance, they are extremely difficult to thin and very expensive.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.
Accordingly, it is an object of the present invention to provide a new and improved method of fabricating a semiconductor device on a thinned substrate.
Another object of the invention is to provide a method of increasing thermal conductivity of a semiconductor device.
And another object of the invention is to provide a new and improved method of fabricating a semiconductor device on a thinned substrate which allows recycling of the substrate.
Still another object of the present invention is to provide a new and improved method of fabricating a semiconductor device on an inexpensive thinned substrate which does not require conventional thinning of expensive substrates thereby reducing costs.